1. Field of the Invention
The present invention pertains to a process for adjusting a friction clutch system such as that used in association with an unsynchronized transmission of a commercial vehicle.
2. Description of the Related Art
Especially when unsynchronized transmissions are used, it is known that a so-called transmission brake or transmission shaft brake can be provided on the friction clutch. During the execution of clutch-release operations, this brake has the effect of decelerating the transmission input shaft connected to the clutch disk or disks when a certain brake-release position is reached. It is necessary in this case for the various phases which occur during the execution of the clutch-release operation to be coordinated so that, in a first release phase, which begins with the clutch in the engaged position, initially only the clutch is actuated, that is, moved in the clutch-release direction. Then, after the clutch has been completely released, for example, further actuation of the clutch-release mechanism brings it into the brake-release position. As a result, depending on the extent to which the clutch has been actuated by the clutch-release mechanism, either only a release operation is performed, as in situations when no braking of the transmission shaft is required, or, if the actuation is strong enough, the brake release position is also reached and the transmission input shaft is braked.
The wear on the friction linings which occurs during the operation of the clutch has the result that the pressure plate, which is usually acted upon by a stored-energy device, moves closer to the flywheel as the thickness of the friction linings decreases. The stored-energy device copies this movement by relaxing and changing its installation position in a corresponding manner in, for example, the engaged state of the clutch. If a comparatively large amount of wear has resulted in a correspondingly pronounced change in the installation position of the stored-energy device, it is possible, during the execution of a clutch-release operation, for the clutch to be brought into its completely released state in the previously described first phase, but impossible for any further actuation, even up to the maximum possible degree of actuation beyond this point, to move the mechanism all the way to the brake-release position. It would thus no longer be possible for the transmission input shaft to be braked.
This problem can be solved, for example, by manually readjusting the clutch-release mechanism during the performance of periodic maintenance work. To do this, the part of the clutch-release mechanism acting on the brake element connected to the transmission input shaft is screwed out, for example, to shift it with respect to the area of the clutch-release mechanism which is connected to the stored-energy device for release movements in common; in this way, the change in the installation position of the area of the clutch-release mechanism connected to the stored-energy device can be compensated. It is thus possible to ensure that the clutch system is adapted to the wear state and that the transmission shaft braking function is preserved.
This manual readjustment is a very complicated operation in itself, but it also brings with it the danger that, for example, if maintenance is neglected or if very severe wear occurs between maintenance intervals, the transmission shaft braking function can be impaired or even lost completely.
It is the task of the present invention to provide measures which ensure that the transmission shaft braking function remains essentially the same throughout the operating life of a friction clutch.
According to a first aspect of the present invention, this task is accomplished by a process for adjusting a friction clutch system, where the friction clutch system comprises: a housing arrangement; a pressure plate; a stored-energy device, which is supported against the housing arrangement and the pressure plate; a wear-compensating device in the path of support between the stored-energy device and the housing arrangement or between the stored-energy device and the pressure plate with a detection element on the pressure plate, which element, in cooperation with a stop element which can be fixed in place with respect to the housing arrangement, detects the wear which has occurred in the system; a clutch-release arrangement, by means of which, to implement clutch-release operations, force can be exerted on the stored-energy device in the direction opposite its relaxation direction; and a transmission shaft brake arrangement, where, upon execution of a clutch-release operation, the transmission shaft braking arrangement is activated when the brake-release position is reached. The adjusting process comprises the following steps: (a) using the clutch-release arrangement to adjust the stored-energy device to a basic pretension position, where, starting from the basic pretension position, a release movement of the clutch-release arrangement by a distance equal to the brake-release stroke allows the brake-release position to be reached; and (b), while the stored-energy device is being held in the basic pretension position, adjusting the stop element and/or of the detection element in such a way that the release of the stored-energy device from the basic pretension position and the subsequent relaxation of the stored-energy device beyond the basic pretension position results in the activation of the wear-compensating device in such a way that, after completion of an adjustment process, the stored-energy device is still essentially in its basic pretension position when the friction clutch is engaged.
A first essential aspect of the present invention is that the clutch is provided with a wear-compensating device, which is basically designed to compensate for the wear which occurs in the area of the friction linings or in the area of the clutch and to keep the stored-energy device in an installation position which is essentially unaffected by wear. This means that, once the friction clutch has been adjusted, it is ensured that any wear which occurs does not lead to any impairment in the transmission shaft braking function which might be caused by a change in the installation position of the stored-energy device.
In addition, however, the present invention also provides measures which take advantage of the adjustment possibility within the friction clutch to ensure that the entire clutch system, when in the new state, can be adjusted so that the various components within the clutch on the one hand and the components in the area of the clutch-release arrangement and the transmission shaft braking arrangement on the other hand are brought into positions such that, again independently of the amount of wear which occurs during operation, only the clutch is actuated in a first defined phase of a clutch-release operation and brought into the completely released position, and that, upon actuation to a defined extent beyond this point, the previously mentioned brake-release position is reached, in which, through activation of the transmission shaft braking arrangement, the braking function is obtained. This therefore means that, once the system has been adjusted, the brake-release stroke required to activate the transmission shaft braking arrangement, i.e., the stroke which starts from the completely engaged position of the friction clutch, will always be the same, regardless of how much the wear has occurred during operation. The need to perform periodic manual adjustments is therefore eliminated.
To produce the braking action, it is possible, for example, for the transmission shaft braking arrangement to be activated by the force exerted on it by a braking element connected to the transmission shaft for rotation in common, the braking element itself being actuated by the clutch-release arrangement. The stored-energy device can easily be brought into the basic pretension position by placing, in step (a), an adjusting spacer between the braking element and the clutch-release arrangement and by actuating the clutch-release arrangement in such a way that it acts on the braking element via the adjusting spacer, the length of this spacer being equal to the brake-release stroke. It is also possible, in step (b), to shift the stop element axially with respect to the housing arrangement in such a way that its contact section comes to rest on the detection element.
In the case of friction clutch systems in which the process according to the invention can be used, it is possible, for example, for the wear-compensating device to comprise: an adjusting element, which can be moved with respect to the pressure plate during the execution of a wear-compensating adjustment, where the stored-energy device acts on the pressure plate by way of the adjusting element; an essentially wedge-like slider, which is pushed by pretension into an intermediate space formed between the pressure plate and the detection element, where the detection element is designed with the elasticity of a spring, one end being attached to the pressure plate, while the other end acts on the slider; and a blocking section on the slider or on the detector element, which limits the adjusting movement of the adjusting element which occurs under pretension.
According to an alternative aspect of the present invention, the previously mentioned task is accomplished by a process for adjusting a friction clutch system, where the friction clutch system comprises: a housing arrangement; a pressure plate; a stored-energy device, which is supported against the housing arrangement and the pressure plate; a wear-compensating device in the path of support between the stored-energy device and the housing arrangement or between the stored-energy device and the pressure plate, which device has a detection element on the pressure plate, which element cooperates with a stop element which can be fixed in place with respect to the housing arrangement to detect the wear which has occurred in the system, where the stop element on the housing arrangement essentially blocks movement in the direction away from the housing arrangement but not in the direction toward the housing arrangement, and where at least one driver area is provided on the stop element, which the stored-energy device approaches during the execution of a release process; a clutch-release arrangement, by means of which force can be exerted on the stored-energy device in the direction opposite its relaxation direction to execute the clutch-release operation; and a transmission shaft braking arrangement, where, upon execution of a clutch-release operation, the transmission shaft braking arrangement is activated when the brake-release position is reached. The adjusting process comprises the following steps: (a) providing the minimum of one driver area on the stop element approximately in such a way that, when the friction clutch system is correctly adjusted, the actuation of the clutch-release arrangement by a brake-release stroke essentially sufficient to reach the brake release position has the result of reducing essentially to zero the distance between the minimum of one driver area and the cooperating area of the stored-energy device, and that, in the engaged state, the detection element is in or near the state of mutual contact with the stop element; (b) positioning the stop element with respect to the housing arrangement in such a way that actuation of the clutch-release arrangement sufficient to reach the brake-release position has the result that the gap between the minimum of one driver area of the stop element and the area of the stored-energy device cooperating with the minimum of one driver area is reduced essentially to zero; and (c) executing of an actuation process of the clutch-release arrangement sufficient to reach the brake release position, where, if the distance between the minimum of one driver area and the stored-energy device is already zero before the brake-release position is reached, the stop element is shifted by the stored-energy device relative to the housing arrangement, i.e., in the direction toward it.
With this procedure, therefore, the execution of an actuating process sufficient to reach the brake-release position has the result that, if the stop element is not already in the correct position, it is now pushed until it assumes the position required for a correctly adjusted clutch. This is so because the driver has already been provided in such a way that it can interact in the correct manner with the stored-energy device. This eliminates the need for any additional adjusting measures and for any manual adjustments during subsequent operation.
It is possible, for example, for the minimum of one driver area to be provided on a driver element which is or can be connected to the stop element by a threaded connection.
The stop element can be held on the housing arrangement by a locking ring element. In a clutch system which can be used in association with this procedure, the wear-compensating device can comprise: an adjusting element, which can move relative to the pressure plate during the execution of an adjusting process, where the stored-energy device acts on the pressure plate by way of the adjusting element; an essentially wedge-shaped slider, which is pushed by pretension into an intermediate space between the pressure plate and the detection element, where the detection element is designed with the elasticity of a spring, one end of which is attached to the pressure plate, while the other end acts on the slider; and a blocking section on the slider or on the detection element, which limits the adjusting movement of the adjusting element which occurs under pretension.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.